A computer network is composed of a set of nodes and a set of links that connect one node to another. For instance, a computer network may be composed of a set of routers while the set of links may be cables between the routers. When a first node in the network sends a message to a second node in the network, the message may pass through many links and many nodes. The links and nodes the message passes through while traveling from the first node to the second node is referred to as a path.
Packet-based computer networks increasingly utilize label switching protocols for traffic engineering and other purposes. In a label switching network, label switching routers (LSRs) use Multi-Protocol Label Switching (MPLS) signaling protocols to establish label switched paths (LSPs). The LSRs utilize MPLS protocols to receive MPLS label mappings from downstream LSRs and to advertise MPLS label mappings to upstream LSRs. When an LSR receives an MPLS packet from an upstream router, it switches the MPLS label according to the information in its forwarding table and forwards the packet to the appropriate downstream LSR.
MPLS can be deployed in core and aggregation network and provides a mature and stable basis for large networks. MPLS can also be used in access networks, e.g. such as mobile or Digital Subscriber Line (DSL) backhaul networks. MPLS is used on two different layers: the Transport Layer and the Service Layer (e.g., for MPLS virtual private networks (VPNs)). In both cases, the protocols and the encapsulation are identical, but the use of MPLS is different especially concerning the signaling, the control plane, the provisioning, the scalability and the frequency of updates. On the service layer, only service specific information is exchanged, and every service can potentially deploy its own architecture and individual protocols. The services run on top of the transport layer.
A Seamless MPLS network is a network in which all forwarding of packets within the network, from the time a packet enters the network until it leaves the network, is done based on MPLS. The motivation of Seamless MPLS is to provide an architecture which supports a wide variety of different services on a single MPLS platform fully integrating access, aggregation and core network. The architecture can be used for residential services, mobile backhaul, business services and supports fast reroute, redundancy and load balancing. Seamless MPLS provides the deployment of service creation points which can be virtually everywhere in the network, enabling network and service providers with a flexible service and service creation. Service creation can be done based on the existing requirements without the needs for dedicated service creation areas on fixed locations. With the flexibility of Seamless MPLS, the service creation can be done anywhere in the network and easily moved between different locations.